Overlay text modification

I can't find the template location for this specific overlay. I want to modify the h1 text which appears to be text that is not acquired from a phrase. Using Search Templates, I couldn't locate "heading h1" in a template.

How do I go about altering the text?

helper_login_form calls the h2 text from a phrase and I could use a different phrase, but it's h1 I'm interested in and h1 is not referenced in this template.

I can't find the template location for this specific overlay. I want to modify the h1 text which appears to be text that is not acquired from a phrase. Using Search Templates, I couldn't locate "heading h1" in a template.

How do I go about altering the text?

helper_login_form calls the h2 text from a phrase and I could use a different phrase, but it's h1 I'm interested in and h1 is not referenced in this template.